1. Field of the Invention
The present invention relates to a power semiconductor device in which reliability can be improved when the number of parallel connection of semiconductor devices increases.
2. Description of the Related Art
A power semiconductor device has a function to convert DC power supplied from a DC power supply into AC power to be supplied to an inductive load such as a motor, or a function to convert AC power generated by a motor into DC power to be supplied to a DC power supply. In order to perform the conversion function, the power semiconductor device includes a power semiconductor device having a switching function, and repeats a conduction operation and an interrupting operation to perform power conversion from DC power to AC power or from AC power to DC power, and the power is controlled.
As related art, patent document 1 (JP-A-9-172139) disclose a technique as described below. Main electrode terminals are arranged to be aligned on almost the same straight line along the longitudinal direction of a resin case. One main surface (inside main surface) of each of the main electrode terminals faces the inside of a case main body part, that is, the side on which an insulating substrate is provided, and all the other main surfaces (outside main surfaces) face the outside of the case main body part, that is, the side opposite to the side on which the insulating substrate is provided. A conducting plate is arranged so that the main surface thereof faces the outside main surface of the main electrode terminal.
Patent document 1 discloses a structure in which two switching devices and two diodes, which are semiconductor devices, are connected in parallel on the insulating substrate (circuit substrate). In order to switch a large current, a circuit of a power semiconductor device is required to be constructed by connecting plural semiconductor devices in parallel correspondingly to the magnitude of the current. When the plural semiconductor devices are connected in parallel, and the parallel number increases, trace distances from electrode terminals as contact surfaces to external electrodes become different from each other, and because of this, a difference in parasitic inductance occurs, and there arises a problem that reliability of the semiconductor device deteriorates.